Which unit would typically be larger in capacity: an RTU or a water heater?

An RTU, or Roof Top Unit, is specifically designed to handle both heating and cooling for commercial or industrial buildings. These units typically have a much larger capacity compared to most residential water heaters. RTUs are rated in tons of cooling or BTUs (British Thermal Units) for heating, often ranging from 2 tons (24,000 BTUs) to over 25 tons or more for larger applications. This is necessary to effectively serve the air conditioning needs of sizable spaces.

In contrast, a standard water heater, even those designed for larger households or commercial use, tends to have a significantly lower capacity. While some high-capacity water heaters can store and heat large volumes of water (measured in gallons), their BTU output for heating is generally lower than that of heating components within an RTU.

The size and capability difference fundamentally stem from their intended applications; RTUs are engineered to provide a comprehensive HVAC solution across large areas, while water heaters focus primarily on delivering hot water for domestic or light commercial use. Thus, the larger capacity and broader functionality of RTUs firmly support why they would be considered larger in capacity compared to water heaters.